Fix, was not bug compatible after optimizing issubclass built-in
Fix, was not bug compatible after optimizing issubclass built-in

* Also add "isinstance" which is very similar code. This is only
  having an effect in full compat code, i.e. mostly when testing
  the CPython test suites, which do issubclass spreading over
  lines a lot.

kayhayen/Nuitka,kayhayen/Nuitka,kayhayen/Nuitka,kayhayen/Nuitka